IPC 7711A.pdf - 第40页
PROCEDURE – LOCAL SPOT REMOVAL 1. Apply Polyimide tape to outline the area where the coating needs to be removed. (See Figure 1.) 2. Dip the end of a foam swab in stripping solution and apply a small amount to the area o…
OUTLINE
This procedure uses a solvent to remove surface coatings. This procedure can be
use for spot or overall coating removal of conformal coatings or solder resists.
Approved solvents may be used to remove specific soluble type coatings on a spot
basis by brushing or swabbing the local area with the controlled application of sol-
vent until the area is free of the coating material.
If warranted, all the soluble type coating can be removed by immersing and brush-
ing the entire printed board or printed board assembly.
To determine the appropriate coating removal procedure the coating must first be
identified. Refer to procedure number 2.3.1.
NOTE
Coating removal may require the use of one or more methods.
CAUTION
Determine, on a module by module basis, the hazards to parts, etc., by short term
immersion in the removal solvents. If chloride based or other harsh solvents are
used, extreme care must be exercised to prevent damage to base material, compo-
nent parts, plated-through holes, and solder joints. Some solvent coating removal
methods can cause expansion or swelling of the base material which can degrade
the printed board or printed board assembly. Under no circumstances should these
solvents be used except in a closely controlled process. It is recommended that the
printed board or printed board assembly be inspected to ensure that no damage has
occurred.
Before using any solvent refer to Material Safety Data Sheets.
REFERENCES
2.1 Handling Electronic Assemblies
2.2 Cleaning
2.3.1 Coating Removal, Identification of Conformal Coatings
2.4.1 Coating Replacement, Solder Resist
2.4.2 Coating Replacement, Conformal Coatings/Encapsulants
TOOLS AND MATERIALS
Brush
Cotton Swab
Polyimide Tape
Knife
Suitable Solvent
Thermal Parting Tool
Wood Stick
Figure 1 Apply tape to outline for
coating removal.
Figure 2 Apply solvent with foam
swab to remove coating.
7711A/7721A
General
Information and
Common Procedures
Revision:
Date: 2/98
Coating Removal,
Solvent Method
Number: 2.3.2
Product Class: R, F, W, C
Skill Level: Advanced
Level of Conformance: High
Material in this manual was voluntarily established by Technical Committees of IPC. This material is advisory only and its use
or adaptation is entirely voluntary. IPC disclaims all liability of any kind as to the use, application, or adaptation of this material.
Users are also wholly responsible for protecting themselves against all claims or liabilities for patent infringement. Equipment
referenced is for the convenience of the user and does not imply endorsement by IPC.
Page1of2
Copyright Association Connecting Electronics Industries
Provided by IHS under license with IPC
Not for Resale
No reproduction or networking permitted without license from IHS
--``,``,-`-`,,`,,`,`,,`---
PROCEDURE – LOCAL SPOT REMOVAL
1. Apply Polyimide tape to outline the area where the coating needs to be removed.
(See Figure 1.)
2. Dip the end of a foam swab in stripping solution and apply a small amount to the
area of coating to be removed. (See Figure 2.)
As an alternative, a small cotton patch can be cut to the size of the area masked
(see Figure 1), saturated with the stripping solution, and pressed into intimate
contact with the surface of the coating to be removed. The patch will retard the
evaporation of certain solvents and reduce exposure time.
NOTE
Since various substances may be used as coatings, the time required for a given
coating to dissolve or soften will vary. Reapply solvent several times as most sol-
vents evaporate rapidly.
3. Rub the treated surface carefully with a brush or wood stick to dislodge the coat-
ing. A wedge shaped applicator tip, knife, or heated blade may be effective in
removing some coatings, particularly polyurethanes.
4. Neutralize or clean the stripped area and dry.
PROCEDURE – OVERALL REMOVAL
1. A single step for removal of all the coating may be completed by providing a con-
tinuous flow of solvent.
Alternately, process the board in a series of tanks containing mild solvent, start-
ing with a high contamination tank and progressing sequentially to a final, fresh
solvent tank.
EVALUATION
1. Visual examination or UV light may be used to verify complete removal of coating.
NOTES
Coating Removal Required at Outlined Areas
IPC-7711A/7721A
Number: 2.3.2
Revision:
Date: 2/98
Subject: Coating Removal, Solvent Method
Page2of2
Copyright Association Connecting Electronics Industries
Provided by IHS under license with IPC
Not for Resale
No reproduction or networking permitted without license from IHS
--``,``,-`-`,,`,,`,`,,`---
OUTLINE
This peeling removal method for coating can be used only under special circum-
stances. Normally this method is used to remove RTV silicone or other thick rubbery-
like coating materials.
The coating material is removed using a dull knife or otherwise dull blade to slit the
coating material and to peel it off the printed board or printed board assembly.
To determine the appropriate coating removal procedure the coating must first be
identified. Refer to procedure number 2.3.1.
NOTE
This method is limited to coatings that are rubbery in nature to allow the coating
material to be slit into small sections and peeled off the printed board assembly.
REFERENCES
2.1 Handling Electronic Assemblies
2.2 Cleaning
2.3.1 Coating Removal, Identification of Conformal Coatings
2.4.1 Coating Replacement, Solder Resist
2.4.2 Coating Replacement, Conformal Coatings/Encapsulants
TOOLS AND MATERIALS
Heated Blade
Knife
Wood Sticks
PROCEDURE
1. Slit and peel off the coating material with a dull knife or heated dull blade. (See
Figure 1.)
2. Repeat as needed until the required material is removed.
EVALUATION
1. Visual examination or UV light may be used to verify complete removal of coating.
NOTE
Coating Removal Required at Outlined Area
Figure 1 Slit and peel off coating
using a knife or heated blade.
Figure 2 Removal complete.
7711A/7721A
General
Information and
Common Procedures
Revision:
Date: 2/98
Coating Removal,
Peeling Method
Number: 2.3.3
Product Class: R, F, W, C
Skill Level: Advanced
Level of Conformance: High
Material in this manual was voluntarily established by Technical Committees of IPC. This material is advisory only and its use
or adaptation is entirely voluntary. IPC disclaims all liability of any kind as to the use, application, or adaptation of this material.
Users are also wholly responsible for protecting themselves against all claims or liabilities for patent infringement. Equipment
referenced is for the convenience of the user and does not imply endorsement by IPC.
Page1of2
Copyright Association Connecting Electronics Industries
Provided by IHS under license with IPC
Not for Resale
No reproduction or networking permitted without license from IHS
--``,``,-`-`,,`,,`,`,,`---